This disclosure is directed to both a method and an apparatus involved in drilling rig construction. Drilling rig construction at a field location in the lower forty-eight states on land normally is no problem. A drilling rig is simply moved by trucks to the location where it is required, unloaded, assembled and left at that location for weeks. When the rig is through drilling, it is either disassembled or simply moved over to a nearby location. It is made in components which are modules sized to fit on a truck and is trucked into and away from the drilling rig site. Off shore, the entire drilling rig is integrated into a barge for drilling in shallow waters, or is arranged in a jack up rig. Even larger versions involve semi-submersible rectangular vessels which have tanks which are partly filled with water to control bouyancy. In all these instances, transportation to and from the area involves either barge traffic or truck traffic. In northern latitudes, the problem is not so easy. At most times of the year, barge traffic is not possible because water is frozen. Truck traffic is not possible because there are literally no roads and the wilderness is simply impassable for trucks. Even where trucks can drive, there is the necessity of building a road of special construction which can be used both winter and summer. The problem is not so much in the winter when the temperatures go perhaps to -50.degree. F. The problem with these roads arises in the summer because such roads require construction of gravel pack on the terrain. In the summer, there is a progressive thawing which may damage the permafrost layer at the top of the earth. The permafrost barrier, once thawed, resembles a sponge and is structurally unreliable. It creates great difficulties in transportation, and also creates comparable difficulties in repair after use. Suffice it to say, such difficulties arise for roads which can be built for heavy traffic (meaning both volume and weight). Gravel roads are not readily available in the northern reaches of the western continents. Effectively, truck traffic is simply forbidden.
By contrast, helicopter lifting can be done in some instances, but helicopters are not able to handle entire drilling rigs. If the rig is broken down, it can be lifted in and out by means of helicopter. That, however, has its own set of problems. Helicopter transportation of rig components is highly desirable in some instances, but it is generally best done to a rig location already implemented. Transportation by helicopter to a rig location (having no landing pad) begs the question ordinarily because it contemplates use of an equipped rig site which is merely serviced by helicopter delivery of freight.
The present disclosure sets out an improved mode of installing a drilling rig at a site that is well off the beaten path, perhaps 100 miles or more away from the nearest work camp. This is certainly true in northern latitudes. It is also true in a number of other circumstances in the lower forty-eight states. To pick an example, the rig site can be at least fifty miles from the nearest road in many areas of Montana, both Dakotas, and Wyoming. The intervening area may be rolling terrain which is essentially prairie with undulating hills. In the four corners area, it may be desert regions or isolated at the far corner of some Indian reservation. In the gulf coast area, the rig site can be in the midst of a swamp including the Florida Everglades, or the delta region of Louisiana. In all these instances, the nearest paved road (or at least gravel service road) is many miles away while the rig needs to be erected, both conveniently and without leaving a destructive trail behind. After well completion, casing the well and connection with a collection line, most of the equipment at the rig site is removed. Indeed, the only thing left visible on the ground is well head equipment for control of fluid production.
Suffice it to say, rigs must be mobilized from a yard or a facility, moved out into the wilderness, travel some distance where roads simply do not exist, erected, and subsequently the rigs are then returned to the storage yard. Each rig site poses comparable problems of lesser or greater scale focusing on transportation to and then from the rig site. To consider now the present disclosure, it sets forth a method and apparatus incorporating hover craft to set up a drilling rig. Moreover, it enables a drilling rig to be put together in the field and removed so that the rig site itself is little disturbed and the immediate vicinity at the rig site is not overburdened by putting the rig there. When the rig is removed, the process is reversed so that the rig components are taken out, substantially in the same fashion, and are removed to another location. With this approach, the rig can be taken apart piece by piece, transported and moved with great ease. The actual velocity of rig movement across the unfriendly terrain is much faster using the present invention than would be the case by transporting it on trailers pulled by heavy duty off road vehicles.
One aspect of the present disclosure features hover craft. There is an industrial sized hover craft readily available which is constructed with a relatively thin dimension (measured vertically), and which has a top located cargo deck. While various sizes exist, a commercially available hover craft is preferably used which has a loading deck measuring 51.times.32 feet having suitable tie downs for support of modular cargo. This kind of device can be loaded at a staging yard and then flown over the terrain leaving minimal disturbance to the terrain. The hover craft when passing over open terrain has a footprint or weight on the ground which is less than a person walking on the ground. Considering an average sized man with a weight of 180 pounds, the weight of that person in conventional shoes is greater than the loading of the hover craft. Considering the same person walking across the snow covered northern latitudes of Alaska and Canada, their weight on typical snow shoes approaches the loading on the ground provided by the present hover craft assisted mobilization procedure. More will be noted regarding that benefit below. In another aspect, the present disclosure contemplates drilling rig construction in the wilderness so that drilling site disturbances are held to a minimum. Where permafrost is involved, the permafrost itself is not disturbed. This avoids creating highly undesirable bogs or soft spots in the area of permafrost damage.
The present disclosure is directed to a method of erecting a drilling rig and will be detailed in the context of northern problems, i.e. permafrost in the earth which is beneath several feet of accumulated snow or ice. In like fashion, the present procedure can be adapted for use in swamps or out on the desert where the footing is shifting sand.